ADU Construction
An accessory dwelling unit is one of the smartest investments a Bay Area homeowner can make. We handle everything — design, permitting, construction, and finishes — to deliver a fully functional living space on your property.
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Building Your ADU from Permits to Keys
Bay Area ADU permitting is complex — every city has different setback requirements, height limits, parking rules, and utility connection standards. We’ve navigated the permitting process in multiple jurisdictions and know what each planning department expects, saving you months of back-and-forth and costly revisions.
We manage the full build: architectural design, foundation, framing, plumbing, electrical, HVAC, insulation, interior finishes, and exterior work including landscaping to restore your yard. You get a fully permitted, fully functional living space with its own entrance, kitchen, and bathroom.
Whether you’re creating rental income, building a space for aging parents, or adding a home office that’s separate from the main house, we’ll design a unit that maximizes your lot’s potential. Most ADU projects in the Bay Area take 4–8 months from permit approval to move-in.
What Shapes the Scope of an ADU
ADU scope varies widely by type. A detached new-build is the most involved — new foundation, walls, roof, systems, and finishes. Garage conversions reuse existing foundation, walls, and roof, which changes the project profile significantly. Junior ADUs carved out of existing living space are the least disruptive when the footprint stays the same.
Lot conditions drive the next big variation. A flat, accessible lot with nearby utilities is the best case. Sloped lots require retaining walls and engineered foundations. Lots with large trees may need arborist reports and root-zone protection. Rocky soil or high water tables can push foundation work significantly.
Utility connections are the surprise line item most homeowners don’t plan for. Sewer laterals, water meters, and electrical service upgrades depend on distance from the main house and whether the utility company requires a separate meter. PG&E service upgrades in particular have gotten slow — plan for 6–12 months of lead time if your main panel needs to be upsized.
City permit fees and timelines vary widely. State ADU law caps most fees, but plan-check review, school district fees, and building permits all still apply and differ by jurisdiction. We walk clients through the specific fee schedule for their city before anyone signs anything.
Common Mistakes Homeowners Make
Starting with a design before understanding what their lot allows is the most expensive mistake. Setback rules, maximum lot coverage, height limits, and tree protection zones all constrain what’s actually buildable. We always run a feasibility study first — a zoning report and a rough site plan — before anyone draws a floor plan.
Underestimating the timeline is the second big one. Most homeowners assume a 6-month project. The reality in most Bay Area cities: 3–6 months for design and permits, 4–8 months for construction, and 1–2 months for utility connections and final inspections. Budget 12–16 months from first consultation to tenant move-in.
Designing for resale instead of use is another pitfall. An ADU designed as a studio may maximize rent today but limit your future options — including fitting aging parents or adult children. A one-bedroom ADU with a real kitchen and a full bath typically commands better long-term rent and works for more life stages.
Finally, not thinking about privacy and noise between the ADU and the main house causes regret after move-in. Window placement, sound insulation in shared walls or ceilings, separate trash and mail areas, and a clearly defined path to the ADU entrance all matter more than homeowners expect.
How Long an ADU Takes to Build
Design and engineering typically take 2–4 months. This includes site survey, architectural design, structural engineering, Title 24 energy compliance, and the final construction drawings that go into permit submittal. Changes to the design after this phase get expensive quickly, so we push hard to finalize plans before submitting permits.
Permit review runs 2–6 months in most Bay Area jurisdictions. State law requires ministerial (non-discretionary) review of code-compliant ADUs, and the state-mandated 60-day review deadline helps, but plan-check corrections, utility clearances, and any deviations from the standard ADU ordinance add time. We handle all correspondence with planning and building departments.
Construction usually runs 4–8 months once permits are issued. Foundation and utility trenching take 2–4 weeks. Framing and roofing add another month. Rough electrical, plumbing, HVAC, and insulation fill the middle. Drywall, finishes, cabinets, and trim run 6–8 weeks. Final inspections and utility connections close out the project.
What to Look for in an ADU Contractor
Ask how many ADUs they’ve completed in your specific city. ADU rules are state-framed but city-implemented, and a contractor who’s built five ADUs in Oakland may still stumble in Palo Alto. You want someone who has walked plans through your planning department before.
Verify they handle design and engineering in-house or with an integrated partner, rather than telling you to hire your own architect and then bidding on the result. ADUs are cost-sensitive projects, and the design phase is where most of the value engineering happens. A builder-designer team working together can shave meaningful cost off the final number.
Confirm they carry current general liability and workers’ comp coverage, that their CSLB license is active and in good standing, and that they’re willing to provide references from clients whose ADUs have been rented out for at least a year. An ADU built to code is one thing; an ADU that holds up to a tenant for years is another.
Why Bay Area Homeowners Choose Genesis
We’ve built ADUs across the Peninsula, the South Bay, San Francisco, and the East Bay. Each jurisdiction has its own quirks — Oakland’s expedited ADU program, San Jose’s pre-approved plans, Palo Alto’s neighborhood-specific design guidelines, San Mateo’s impact-fee rules — and we know how to move through each one efficiently.
Genesis handles the entire ADU from concept to keys: feasibility, design, structural and energy engineering, permit submittal, construction, utility coordination, and final move-in walkthrough. You have one contract, one point of contact, and one schedule — not a chain of architects, engineers, and subcontractors you have to manage yourself.
Because ADUs are often built as income properties, we pay particular attention to durability and tenant-ready finishes: quartz rather than marble, LVP rather than hardwood in heavy-wear areas, and fixtures chosen for easy replacement. The ADU should earn for you for decades, not create a maintenance burden.
What Our Clients Say
“Built an ADU in our backyard for my mother-in-law. Genesis handled all the permitting with the city, which saved us months of headaches. The finished...”
Tom R.
ADU
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